Technical Field
The present disclosure relates to a drug administration instrument for administering drug into a body, various medical devices, infusion containers, and the like.
Background Art
In recent years, prefilled syringes whose syringe is prefilled with a medicinal fluid (drug administration instruments) have been used widely. In administering medicinal fluid using such prefilled syringe, there is no need to draw the medicinal fluid from a vial (bottle) into the syringe, whereby time required for administration can be saved.
In general, a prefilled syringe includes a stationary part and a plunger. To administer a drug into the body using a prefilled syringe, the plunger is operated so that the drug in a liquid chamber in the stationary part is released in vivo via a needle connected to the barrel end of the stationary part.
In administering a relatively small dose of the drug, a compact prefilled syringe having a small liquid chamber is used. For example, to insert the needle perpendicular to the skin and inject the drug into the upper layer of the skin, a considerable pressure to the injection site is required, and the prefilled syringe must be firmly held against the skin in order to prevent leakage of the drug. However, conventional compact prefilled syringes do not have a suitable structure to remain firmly held against the skin, making them difficult to use. Another challenge for users is that, even though a compact prefilled syringe having a small liquid quality is used for administering a small amount of the drug on the order of 0.05-0.5 mL taking into account drug delivery to the upper layer of the skin, it is difficult to keep track of the movement of the plunger. Thus, there is a need for an injection technique in which a user is able to know when the injection is completed.
A drug administration instrument with increased operability is described in JP 2011-212185 A, for example. The drug administration instrument described in JP 2011-212185 A has a barrel having a liquid chamber for storing a drug, a pusher to be passed inside the barrel, a grip, and a connecting part. The pusher includes a rod-like plunger and a gasket. The grip is disposed along an outer circumference of the barrel, and the connecting part is formed between the barrel and an end of the grip. In the drug administration instrument described in JP 2011-212185 A, because the grip is disposed along the outer circumference of the barrel, the grip is easy to hold, whereby a user can apply more force to the pusher.
However, the grip and the barrel for the drug administration instrument described in JP 2011-212185 A are integrally molded, and the barrel has a dual-tube structure partially. As a result, for the drug administration instrument described in JP 2011-212185 A, it is necessary to additionally manufacture a syringe, and the structure of a die for molding the syringe is complicated.
Because the syringe of a prefilled syringe is prefilled with a drug, such prefilled syringe requires a drug filling process. For example, in the case of injection into an upper layer of the skin, a typical dose is on the order of 0.03-0.5 mL. In general, a versatile high-speed drug filling machine is used for filling the syringes with the drug. However, for the drug administration instrument described in JP 2011-212185 A, such a versatile high-speed drug filling machine is not usable because of the unique shape of the syringe. Therefore, modification of the high-speed drug filling machine may be necessary and/or the drug filling efficiency is lowered.